A novel protein has been identified on the surface of mycobacteria including M. tuberculosis, the causative agent of TB, which appears to promote the interaction of mycobacteria with host cells. Methods have been developed for the purification of this protein. the gene has been cloned and sequenced from both M. tuberculosis and M. bovis. Evidence suggests that this protein is glycosylated and that this effects both function and immunogenicity. Important binding sites and immunological epitopes will continue to be characterized. The role of this protein in attachment of mycobacteria to host tissues and in other bacterial interactions continues to be investigated in detail.